Such a cutter head (also referred to as cutter) is for instance known from NL-A-9200368. Described in NL-A-9200368 is a cutter head in the form of a rotation-symmetrical revolving body which is rotatable about a rotation axis by means of drive means and which is provided along its peripheral surface with a number of cutting tools for penetrating into the ground. The cutter head is connected to a suction conduit for discharging the loosened ground. The known revolving body takes a conical form and comprises a number of spiral-shaped ribs running between two circular end sides. The spiral-shaped ribs are provided with cutting tools. The rotation axis of the known cutter head runs substantially parallel to the longitudinal direction of the ladder to which it is attached. A similar cutter dredger is disclosed in JP 61112065.
The cutter head is applied in combination with a cutter suction dredger (also referred to as cutter dredger). Such a cutter suction dredger comprises a ship anchored in the ground by means of spud posts. This anchoring creates a means for absorbing and transmitting to the ground the generally considerable reaction forces occurring during dredging. The ladder here forms a substantially rigid connection between the cutter head and the cutter suction dredger. In order to enable removal of the dredged ground a suction conduit, which is connected to the cutter head, is usually fixed to the ladder. During dredging the cutter head with ladder and suction conduit is usually lowered into the water at a generally oblique angle until it touches the ground. The cutter head is then set into rotation and dragged through the ground by hauling the ladder alternately from port side to starboard side using winches. The cutter head hereby makes a lateral sweeping movement through the ground. By rotating the cutter head round the rotation axis the cutting tools strike the ground with great force with their tips under the weight of the cutter head, ladder and suction conduit. The ground is eventually broken into large fragments by the repetitive hammer blows of the successive cutting tools. These fragments are suctioned up by the suction conduit and discharged. A whole ground surface can be dredged by moving the cutter suction dredger over a determined distance at a time and repeating the above stated sweeping movement.
In order to protect the cutting tools to some extent from excessive wear, the rotation speeds of the known cutter head are generally limited to 20 to 40 rotations/minute. This has the drawback that the efficiency of the dredging operation, particularly in the case of (hard) grounds with a high Unconfined Compressive Strength (UCS) is often insufficient. Efficiency is understood in the context of this application to mean the volume of ground which can be dredged per unit of time and unit of power.